aboutsummaryrefslogtreecommitdiffstats
path: root/Documentation/device-mapper
diff options
context:
space:
mode:
authorHeinz Mauelshagen <mauelshagen@redhat.com>2007-05-09 05:33:06 -0400
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-05-09 15:30:47 -0400
commit26b9f228703f0518a90e7513d6fe7b6abeed5138 (patch)
tree3437e92667c338ea46ad47b064ce4908d7d75fe2 /Documentation/device-mapper
parent0ba699347e96b5468b42b3decf1f381abbf99652 (diff)
dm: delay target
New device-mapper target that can delay I/O (for testing). Reads can be separated from writes, redirected to different underlying devices and delayed by differing amounts of time. Signed-off-by: Heinz Mauelshagen <mauelshagen@redhat.com> Signed-off-by: Milan Broz <mbroz@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation/device-mapper')
-rw-r--r--Documentation/device-mapper/delay.txt26
1 files changed, 26 insertions, 0 deletions
diff --git a/Documentation/device-mapper/delay.txt b/Documentation/device-mapper/delay.txt
new file mode 100644
index 000000000000..15adc55359e5
--- /dev/null
+++ b/Documentation/device-mapper/delay.txt
@@ -0,0 +1,26 @@
1dm-delay
2========
3
4Device-Mapper's "delay" target delays reads and/or writes
5and maps them to different devices.
6
7Parameters:
8 <device> <offset> <delay> [<write_device> <write_offset> <write_delay>]
9
10With separate write parameters, the first set is only used for reads.
11Delays are specified in milliseconds.
12
13Example scripts
14===============
15[[
16#!/bin/sh
17# Create device delaying rw operation for 500ms
18echo "0 `blockdev --getsize $1` delay $1 0 500" | dmsetup create delayed
19]]
20
21[[
22#!/bin/sh
23# Create device delaying only write operation for 500ms and
24# splitting reads and writes to different devices $1 $2
25echo "0 `blockdev --getsize $1` delay $1 0 0 $2 0 500" | dmsetup create delayed
26]]